The dye DCM, [2-[2-[4-(dimethylamino)phenyl]ethenyl]-6-methyl-4H-pyran-4-ylidene]propan edini advantageous for use in certain dye lasers, particularly for argon laser pumped continuous wave operation in the deep red. Such dye lasers typically employ a jet stream of the dye in a viscous solvent such as ethylene glycol as a component of the laser cavity. The dye DCM, however, dissolved in a mixture of benzyl alcohol and ethylene glycol (typically 40:60 volume:volume ratio) has initial acceptable laser performance, but it quickly degrades over several days, even if the laser is not running. The degradation is caused by precipitation of the dye on filters, requiring the dye solution to be changed relatively often. Moreover, since ethylene glycol is hygroscopic, the composition of the dye solution changes since ethylene glycol gains as much as 15% of its own weight in water from the atmosphere within a few days. From a safety point of view, DCM is a known, strong mutagen, and hence it is suspected to be a carcinogen.
Therefore, there is a need for developing improved dye systems to obviate some or all of these problems with the DCM/benzyl alcohol/ethylene glycol dye system.